An ad-hoc network is a typically a dynamic collection of nodes capable of communicating therebetween without the aid of pre-established infrastructure. Ad-hoc networks differ from traditional networks in that the topology of interconnections between nodes is inherently dynamic and not fixed. Consequently, ad-hoc networks do not rely on a centralized authority in order to coordinate the communication between the nodes.
A number of routing protocols used to implement ad-hoc networks have been presented in the literature. Generally, the routing protocols belong to two groups: proactive and reactive. Proactive protocols attempt to maintain correct and up-to-date routing information at every node. This information is then used to establish connections between the nodes that wish to communicate. Reactive protocols, in turn, collect necessary routing information only if a pair of nodes are to establish a communication.
Many existing ad-hoc network protocols are rather complex, which seems to be one of the reasons why ad-hoc devices utilizing ad-hoc protocols are not widely available. Considering a highly dynamic nature of ad-hoc networks, that frequent change in their topology, it is the opinion of those of skill in the art that reactive protocols are more suitable for use in this environment. Furthermore, overhead associated with maintaining up-to-date routing information at every node in an ad-hoc network is known to be expensive.
The dynamic environment of ad-hoc networks calls for new routing protocols to be implemented, since the traditional routing protocols are not current with frequent topology changes that occur in ad-hoc networks.